The present invention relates to a portable electro-optical device.
Portable electro-optical devices comprising an optical/electronic module and an external casing which contains the module are known. Devices of this type consist, for example, of laser guns for reading optical codes. In these devices the optical/electronic module comprises an optical unit and an electronic unit for controlling the optical unit and processing the signal. The optical unit contains a laser source which emits a laser beam and optical components for focusing and driving the laser beam. The optical components comprise movable mirrors which, depending on the technology used, are connected to a stepper motor or mounted on a resilient support. The electronic unit contains electronic components which are mounted on a printed circuit (or board) which also carries the optical components.
These devices, and in particular laser guns, are manually operated by operators and it happens that, during use, they are frequently dropped. The external casing of the devices is fairly strong and is able to withstand the impacts, but it transmits to the optical/electronic module, which is fairly delicate, stresses which often impair correct operation thereof. In fact, on account of the frequent impacts, displacements of the optical components occur, with consequent misalignment of the laser beam and also damage and breakage of the optical and electronic components.
Problems of an entirely similar nature are encountered in optical code readers which use an LED illumination system and sensors of the CCD (Charged Coupled Device) type or CMOS (Complementary Metal Oxide Semiconductor) type.
In an attempt to solve the problem, bearings made of visco-elastic material have been used, said bearings being arranged between the external casing and the board supporting the optical and electronic units. In particular, annular rubber bearings are generally used, being mounted on brackets fixed to the board and housed in seats formed in the casing.
However, this solution has proved to be unsatisfactory because, in various situations, twisting of the board has been found to occur, resulting in misalignment of the optical components and also detachment and/or breakage of optical or electronic components.
The inventors have realised that, in the above-mentioned conditions, these drawbacks are due to the fact that the rubber bearings are able to protect the optical and electronic components only in the case of stresses due to impact forces which are substantially perpendicular to their bases, namely parallel to the longitudinal axis of the bearings. On the other hand, they are often unable to withstand effectively stresses due to impact forces which are differently oriented, for example shearing forces, which are substantially parallel to the bases of the bearings, or inclined forces. In these circumstances, all the forces acting on the casing are transmitted to the board in a more or less direct manner and are concentrated in restricted zones of the board, causing the above-mentioned damage.
The object of the present invention is to eliminate the above-mentioned drawbacks.
The above-mentioned object is achieved, in accordance with the invention, by means of a portable electro-optical device comprising an optical/electronic module comprising an optical unit and an electronic unit and an external casing designed to contain said module, characterized in that it also comprises a supporting structure arranged between said module and said external casing, said structure being capable of ensuring that said module is kept substantially protected from impact stresses which are due to accidental dropping during use of said device by an operator and act in any direction on said casing.
In one embodiment, said supporting structure is of the controlled deformation type and is capable of dissipating energy resulting from said impact stresses.
In particular, said optical unit and said electronic unit are mounted on a board and said board is housed in said supporting structure.
Advantageously, said supporting structure comprises a frame which supports said board and is provided with pins for connection to said external casing.
Preferably, said board is provided with at least one hole and said frame is provided with at least one hollow stud designed to penetrate into said hole so as to be fixed to said board.
Moreover, said board is provided with at least one eyelet and said frame is provided with at least one element, preferably in the form of a tooth, designed to engage with said eyelet so as to retain said board in said frame in the longitudinal direction.
Preferably, said frame is provided with bearing lugs for said board and at least one resilient tongue designed to co-operate with at least one lug in order to retain vertically said board in said frame.
In another embodiment, visco-elastic elements are arranged between said support frame and said external casing.
Advantageously, said visco-elastic elements are rubber bearings.
In particular, said rubber bearings are ring-shaped and are mounted on said pins.
Preferably, said casing comprises a base and a cover, said base and cover being provided with respective half-seats designed to house said pins.
Advantageously, said half-seats are designed to house said bearings as well.
Preferably, said support frame is made of semi-rigid material. For example, it consists of a polymer material chosen from the group comprising: nylon, acetal resins, polycarbonates and the like.
According to a variant, said support frame is made of rigid material.
According to another variant, said support frame is made of substantially resilient material.
In particular, said optical unit comprises a laser source which emits a laser beam and optical components for focusing and driving said laser beam.
According to a variant, said optical unit comprises a diffused light source and a sensor of the CCD or CMOS type.
In the event of accidental dropping during use thereof by an operator, the electro-optical device according to the invention has the advantage that the optical/electronic module remains correctly positioned in the frame without damage to components and without the laser beam undergoing misalignment.